The present technology generally relates to the use of fiber optics to measure position. More particularly, the present technology relates to magneto-optic position detection in aviation environments.
Conventional methods of measuring position include linear variable differential transformers (LVDT), laser vibrometers, optical gap sensors, Hall-effect sensors, etc. Some of these techniques are mature but cannot be used in some harsh environments such as experienced by aviation controls. Other techniques such as the LVDT are currently used in measuring position, but have a certain space and weight limit associated with them. Current position measurement systems that rely on linearly variable differential transformers are relatively bulky and require heavy shielded wiring from the measurement point to the full authority digital engine control (FADEC). The number of sense points on an engine may number in the hundreds. The relative size and weight of these sensors and their wiring becomes a significant issue. Hall-effect sensors are currently being looked at as potential replacement for LVDT based sensors, however they are still in the development/test phase.
Although there have been several approaches to magneto-optic position sensing, most of them are limited in range as they use the magnitude of magnetic field as a mechanism. As magnetic field decays rapidly away from magnet, this approach has a limited range. One approach uses a magnetic encoder plate but it is limited by the complexity of multiple fibers. Another approach uses multiple magnets to create a relatively large length over which the magnitude of the magnetic field remains relatively constant.